Plow trip mechanism

ABSTRACT

A safety trip mechanism for a plow which permits a plow to raise up, move rearwardly and pivot upon striking a buried object and which mechanism returns the plow to operative position after the object has been cleared.

United States Patent Inventors Richard G. Moe [5 6] References Cited LaCrosse; UNITED STATES PATENTS S w ff?" fi' f 2,730,029 1/1956 Brundage172/484 x A l N es 3,295,612 l/1967 Mayo et a1. 172/699 x J S 25 19683,349,855 10/1967 Knudson 172/265 ux Pateemed 12 1971 3,461,971 8/1969Sprenkel 172/710 Assignee Allis-Chalmers Manufacturing Company FOREIGNPATENTS Milwaukee, Wis. 304,070 5/ 1917 Germany 172/265 449,328 7/1926Germany 172/699 1,207,129 12/1965 Germany 172/710 Primary ExaminerC1ydeI. Coughenour PLOW TRIP MECHANISM ntgirreysglgenneth C. McKivett,Charles L. Schwab and 4 Claims, 10 Drawing Figs. 0 en enson us. c1 .1172/265, 1

172/484, 172/710 ABSTRACT: A safety trip mechanism for a plow which per-Int. Cl A01b 61/04 mits a plow to raise up, move rearwardly and pivotupon strik- Field of Search 172/265, ing a buried object and whichmechanism returns the plow to 699, 484, 710 operative position after theobject-has been cleared.

' 1 i 1 f Till/I7 I u u H-U' 1 4 '2 56 1 o 2 I o 23/ 66 PATENTED AUG]"(I971 3599.728

sum 3 or 4 QMpR/ M PLOW TRIP MECHANISM This invention relates tomoldboard plows and more particularly to the type that are individuallyself-restoring.

An object of this invention is to provide a self-restoring plow tripmechanism-of the hydraulic type wherein a tripping of such mechanism toclear small obstructions results in a I under the frame of the plow.

A further object of this invention is to provide a self-restoring plowtrip mechanism wherein the tripping arc is short and is traversedrapidly leaving substantially no skipped or unplowed ground.

A further object of this invention is to provide a self-restoring plowtrip mechanism utilizing a hydraulic cylinder and wherein the rod of thecylinder is ordinarily protected and only extended during a trippingoperation.

A further object of this invention is to provide easily operated meansfor retaining a plow bottom in tripped position to provide easy accessto the plow bottom.

A further object of t is invention is to provide a self-restoring plowtrip mechanism utilizing a hydraulic cylinder and wherein an elastomericspring may be substituted directly for such cylinder.

A further object of this invention is to provide a self-restoring plowtrip mechanism wherein the geometry of the trip mechanism is such thatthe plow trips without any portion of the plow traveling below thefurrow bottom.

A further object of this invention is to provide a self-restoring plowtrip mechanism wherein either a hydraulic cylinder, an elastomerictension spring or an elastomeric compression spring may be usedtherewith for returning a tripped plow to functioning position.

A further object of this invention is to provide-a self-restoring plowtrip mechanism wherein such mechanism functions according to the objectit has contacted; if the object is small the mechanism returns the plowto plowing position without changing the plowing aspect thereof and iflarge the mechanism rapidly removes the plow from the ground and returnsit so as to minimize the unplowed area created in the plowing furrow.

A further object of this invention is to provide a self-restoring plowtrip mechanism of simple inexpensive design.

A further object of'this invention is the provision of an improvedimplement trip wherein the plow bottom is carried upon a supportingframe by generally parallel links which are biased downwardly tomaintain the bottom in plowing position but which permits the plowbottom to rise in response to objects being contacted and which onlywithdraws the bottom from the ground in response to abnormal conditions.

A further object of this invention is to provide an elastomeric tensionspring wherein stepped metal ends provide adequate bonding for theelastomer so that maximum stress is at the smallest diameter of themetal and greatest of the elastomer.

A further object of this invention is to provide an elastomericcompression spring which is so proportioned that a columnar effect isachieved, thereby producing only compressive deflection at ordinaryoperating loads.

Other objects, purposes and advantages of the invention will hereinaftermore fully appear or will be understood from the following descriptionof trip mechanisms constructed in accordance therewith and adapted foruse with a moldboard plow, the mechanism being illustrated in theaccompanying drawings in which:

FIG. 1 is a side elevation of a plow embodying the invention shown inplowing position; I

FIG. 2 is an end view of the plow shown in FIG. 1;

FIG. 3 is a side view similar to FIG. 1 but showing the plow in fulltripped position;

FIG. 4 is a side view similar to FIGS. 1 and 3 showing the path oftravel of the plow as it is tripped to its maximum position;

FIG. 5 is a plan view of two plows similar to that shown in FIG. 1 andshowing the hydraulic accumulator connected to the plows;

FIG. 6 is a diagrammatic showing of the hydraulic accumulator shown inFIG. 5;

FIG. 7 is a side elevation of a plow similar to FIG. 1 but showing anelastomeric tension spring substituted for the hydraulic cylinder ofFIG. 1;

FIG. 8 is a longitudinal section view through the elastomeric tensionspring shown in FIG. 7;

FIG. 9 is a side elevation view of a plow similar to. FIG. 7 but showingan elastomeric compression spring substituted for the A further objectof this invention is to provide an elastomeric tension spring whereinthe cross section of the midportion of the spring is proportioned toallow maximum uniform elongation out in the main body area, therebyrealizing the full tensile potential of the material. As the spring isextended, crosssectional area is decreased, which tends to reduce theload required for further extension thereby flattening theloaddeflection curve, which is desirable and very difficult to achievewith conventional springs.

hydraulic cylinder of FIG. 1; and,

FIG. 10 is a longitudinal section view through the elastomericcompression spring shown in FIG. 9.

In the drawings plow-supporting frame 11 in FIG. 1 is shown supportingone plow bottom 12. Ordinarily, there would be a plurality of such plowssupported on such frame, however, the remaining plows would function thesame as the plow herein described. A supporting framework 13 is attachedto the underside of frame 11 by means of bolts 14 and nuts 16 contactingbracing members 17. Framework 13 includes a horizontal portion 18 incontact with the underside of frame 11 and vertical side portions 19 and21 extending generally vertically from the underside of frame 11.

Adjacent the reanvard right-hand end of horizontal portion 18 a U-shapedbracket 22 is attached thereto as by welding. Bracket 22 has alignedopenings 23 therein for receiving a pivot pin 24. Between the sidewallportions of bracket 22, a collar 26 is received about pivot pin 24 andis attached thereto by means of pin 27. Attached to collar 26 as bywelding are link 28 and bell crank arm 29. Arm 29 has its outer endpivotally connected to the piston end of hydraulic cylinder 31 by meansof pin 32. The other end of cylinder 31 is pivotally connected to pin 33carried by members 19 and 21 of framework 13. Referring to FIGS. 5 and 6the piston end of cylinder 31 is hydraulically connected to anaccumulator 34 by means of tube 36 and tube 37. Accumulator 34 isattached to frame 38 by means of bands 39.

Referring to FIG. 6 accumulator 34 is made up of two portions; oneportion 41 is hydraulically connected to line 37 and contains ordinaryhydraulic fluid. The other portion 42 of accumulator 34 containsnitrogen gas which is separated from portion 41 by means of a suitablediaphragm 43. A connection 44 is provided for charging 42 with nitrogenwhen required. Means for charging portion 41 with the desired amount ofhydraulic fluid is provided by a tractor hydraulic system (not shown)but includes a line 46 connected to line 37 and connectable to a tractorhydraulic system by means of a coupling 47. A gauge 48 is installed inline 46 so the desired amount of hydraulic pressure can be readilydetermined. A shutoff valve 49 is also installed in line 46 so that line46 can be discon nected from line 37 when accumulator portion 41 hasbeen charged with sufficient hydraulic fluid at a desired pressure.

opening for receiving a fastener 52. A link 53 is provided with abifurcated end 54 (see FIG. 2) which pivotally receives fastener 52.Bifurcated end 54 also receives end portion 51. The other end of link 53is attached to a collar 56 which is in turn pivotally attached to plowstub beam 57 by means of fastener 58.

The other end of link 28 is attached to a collar 59 as by welding andwhich is pivotally connected to a midportion of stub beam 57 by means ofbolt 61. Link 28 has a stop member 62 attached at a .midportion thereof.This stop member 62 contacts stub beam 57 to limit the downward movementof plow stub beam 57 and plow bottom 12 to the position shown in FIG. 1.If desired, link 28, collar 26, arm 29, collar 59, and stop 62 can becast as a unitary member rather than being fabricated as previouslydescribed. 1

Link 53 is provided with a hook portion 63 adjacent fastener 58 whichwill coact with any desired cylindrical rod or the like such as ascrewdriver which will fit into opening 64 t o retain plow stub beam 57in the raised position shown in .FIG. 3. This is a handy feature when itis desired to change the plow share 66 or any part of plow bottom 12. Ifthe plow share 66 became damaged pin32 can be removed disconnectinghydraulic cylinder 31 from arm 29.T he plow can now be manually raisedto the position show in FIG. 3, and a screwdriver or the like can beinserted in opening 64 and positioned under hook 63 for retaining theplow assembly in the position shown in FIG. 3 until the desired repairsare accomplished. Then the screwdriver or the like would be removed fromunder hook 63 and from opening 64. The plow would be returned to itslowered position and the hydraulic cylinder 31 would be reconnected toarm 29.

In FIG. 1 a disc coulter 67 is shown mounted forwardly of plow bottom12. Disc coulter 67 is mounted on frame 11 in a conventional manner.

Referring to FIG. 4 it is seen how the previously described plowfunctions when it strikes a stone 68. Upon striking the stone, the plowmoves backwards and upwardly as shown by the lower set of arrows. Links28 and 53 are substantially parallel when plow is in plowing positionand during the first part (from position A to position B) of the raisingmovement (a matter ofl or 2 inches) plow 12 substantially retains itsnormal plowing aspect because of this substantially parallel linkage. Asthe raising continues from position B toC to D and E the point of theplow begins to point downwardly as more pivoted movement is given to theplow thereby permitting the plow to rid itselfof obstructions.

One of the advantages of this construction is that the plow only raiseshigh enough to clear the obstruction encountered whereas prior artdevices cycled through a complete lift and would leave an unplowed areaeven for a relatively minor obstructionf In other words, for arelatively small obstruction,

the plow of the present invention might raise to the B position or lessand immediately return to its full plowing position A or if theobstruction was greater it might raise to the C or D position but wouldimmediately return to the plowing position A when the obstruction waseliminated and therefore by only raisingsufficient toclear theobstruction a large transfer of hydraulic fluid is eliminated, thuspermitting several plows operating from one accumulator.

The force that returns plow I2 to its plowing position is the forcesupplied by the accumulator. Originally the accumulator is provided witha balanced loading of nitrogen and hydraulic fluid so that the desiredforce for keeping the plow in plowing position for normal operation isobtained. Then when the plow strikes an obstruction and starts movingbackwards piston 69 in cylinder 31- moves toward the right in FIG. 6forcing the hydraulic fluid back into line 37 and portion 41 of theaccumulator compressing diaphragm 43 against the nitrogen gas andthereby compressing the gas. When the plow has cleared the obstructionthen the force built up by compression of the nitrogen gas acts uponpiston 69 to return the plow to plowing position.

Referring to FIGS. 7 through 10 it is seen that elastomeric (an elasticpolymer such as polyurethane) springs may be substituted for thehydraulic accumulator system already discussed. In FIG. 7 an elastomerictension spring assembly 71 has been substituted for the hydrauliccylinder 31 of FIG. 1. This assembly 71 (see FIG. 8) includes anelastomeric cylinder 72 bonded internally at each end to steppedinternally threaded metal inserts 73 and 74. From viewing FIG. 8 it isapparent that elastomeric cylinder 72 has its thickest section at linesAA and B-B. The stepped metal end of inserts 73 and 74' provide adequatebonding surface and the elastomeric cross section increases as thestress increases. As previously stated, maximum stress is at thesmallest diameter end of the metal inserts. From that point theelastomeric cross section is then decreased toward the longitudinalcenter of the elastomeric cylinder to allow maximum uniform elongationout in the main body area between line C and D, thereby realizing thefull tensile potential of the material. As this spring is extended thecross-sectional area is decreased, which tends to reduce the loadrequired for further extension thereby flattening the load-deflectioncurve, which is desirable and very difficult to achieve with metalsprings. Eye bolt 76 and yoke member 77 are threadably engaged withinserts 73 and 74,' respectively, so that the assembly may be directlysubstituted for hydraulic cylinder 31 in FIG. 7.

Referring toFIGS. 9 and 10 it is seen how elastomeric compressionsprings may be substituted for the elastomeric tension springs of FIG.7. Individual elastomeric spring sections 78 are mounted about aninternal rod 79 having a portion 81 attached at one end thereof as bywelding. This portion 81 is pivotally connected to arm 29 as by pin32.'A pair of brackets 82 (only one of which is shown) are bolted toopposite sides of frame 11 and pivotally support a U-channel member 83by means of a pair of aligned pivot fasteners 84 (only one of which isshown). The rear of the right-hand end of channel member 83 is closed byplate 86 which is provided with an opening through which rod 79 extends.Each spring section 78 is provided with a washer spacer 87 mounted aboutrod 79 and these washer spacers abut each other between adjacent springssections 78. Washer 88 is adjustably retained on red 79 by nut 89 whichis threadably engaged with the left-hand end of rod 79. The preloadingon springs 78 can be accomplished by turning nut 89 relative to rod 79thereby compressing springs 78 between washer 88 and plate 86.

From the foregoing it is apparent that when the plow strikes a stone orthe like the plow will move rearward and upwardly as previouslydescribed concerning FIG. 1. This causes rod 79 to move generally towardthe right as viewed in FIG. 9. This movement of rod 79 causes washer 88to move rearward contacting spiings 78 and compressing them betweenwasher 88 and plate 86. During this compression process the entirespring assembly will pivot about the bolts 84 as arm 29 moves rod to theright. Like the tension elastomeric spring, this compression spring 78is also very successful in achieving a flat load-deflection curve.Spring section 78 is so shaped that upon I loading the spring a columnareffect is achieved thereby producing only compressive deflection atnormal operation loads. Since the column as seen in FIG. 10 is notstraight and has a greater diameter at the center than at the ends,failure of the columnar effect can be predicted and will collapse at thelargest diameter. From that moment on, increased loading causes bendingof the spring wall at the large diameter. This puts the elastomericmaterial in tension at that point and will resist increased loading (butless effectively than when the columnar effect was present) whichproduces the flat portion of the curve. Finally, as load is applied, thespring assumes the shape of a torus and the ends make contact with eachother. At this point, the load-deflection curve rises rapidly and theeffective useablc deflection has been fully utilized.

The use of washer spacers 87 between compression springs 78 also effectsthe load-deflection curve since drag on the natural rod 79 is reducedand the elastomeric material will flow around the spacer resulting inmore total deflection before the upper limit is reached.

From the foregoing it is seen that an improved plow trip linkage of theself-restoring type has been provided and that this linkage isinexpensive and consists of few parts of com- 7 mon configuration and itis adapted for use with a hydraulic cylinder and accumulator system, orwith an elastomeric tension spring substituted for such hydrauliccylinder and accumulator system or with an elastomeric compressionspring substituted for the tension spring.

While the preferred construction in which the principles of the presentinvention have been incorporated is s own and described herein, it is tobe understood thatthe invention is not to be limited to the particulardetails, shown and described herein, but that in fact, widely differentmeans may be employed in the practice of the broader aspects of thisinvention.

The embodiments of the invention in which we claim an exclusive propertyor privilege are defined as follows:

1. A self-restoring plow trip comprising a supporting frame, a moldboardplow attached to a stub beam, a pair of vertically spaced solid linkspivotally connected at their forward ends to said supporting frame andat their rear ends to said stub beam, biasing means connected betweenone of said links and said frame for biasing said stub beam into plowingposition, in all positions of said plow said pivotal connection of thelower of said links and said frame being positioned forwardly of thepivotal connection of the upper of said links'with said frame and saidpivotal connection of said lower link and said stub beam beingpositioned rearwardly of the pivotal connection of said upper link withsaid stub beam whereby when said plow strikes an object said plow willmove rearwardly and upwardly without the point of said plow striking thebottom of said plow furrow, one of said links is provided with a stopmember coacting with said stub beam for limiting the forward movement ofsaid plow under the influence of said biasing means.

2. A self-restoring plow trip as recited in claim 1 and wherein saidupper link is provided with a hook portion coactable with a memberinserted through an opening in said stub beam for retaining said plow intripped position.

3. A self-restoring plow trip comprising a supporting frame,

a moldboard plow attached to a stub beam, a pair of vertically spacedsolid links pivotally connected at their forward ends to said supportingframe and at their rear ends to said stub beam, biasing means connectedbetween one of said links and said frame for biasing said stub beam intoplowing position, in all positions of said'plow said pivotal connectionof the lower of said links and said frame being positioned forwardly ofthe pivotal connection of the upper of said links with said frame andsaid pivotal connection of said lower link and said stub beam beingpositioned rearwardly of the pivotal connection of said upper link withsaid stub beam whereby when said plow strikes an object said plow willmove rearwardly and upwardly without the point of said plow striking thebottom of the plow furrow, said upper link is approximately one-half thelength of said lower link and is vertically spaced therefrom to providesaid plow with a twofold tripping action when an object is struck, afirst action of moving backwards principally while maintaining a plowingaspect of the plow, a second action of pivoting the plow as it is movedrearwardly,'and said biasing means comprises a hydraulic cylinderpivotally connected at one end to said frame and pivotally connected atthe other end thereof to a crank arm of one of said links, saidhydraulic cylinder being hydraulically connected to an accumulatorcarried by said frame for providing a hydraulic force resisting upwardmovement of said plow and for storing energy provided by the upwardmovement of said plow.

4. A self-restoring plow trip comprising a supporting frame, a moldboardplow attached to a stub beam, a pair of vertically spaced solid linksconnected at their forward ends to said supporting frame rearwardly ofthe forward point of said plow when in plowing position and sad llflkSbeing connected at their rear ends to said stub beam, biasing meansconnected between one of said links and said frame for biasing said stubbeam into plowing position and permitting relief upon striking anobject, in all positions of said plow said pivotal connection of thelower of said links and said frame being positioned for-. wardly of thepivotal connection of the upper of said links with said frame and saidpivotal connection of said lower link and said stub beam beingpositioned rearwardly of the pivotal connection of said upper link withsaid stub beam whereby when said plow strikes an object said plow willmove rearwardly and upwardly without the point of said plow striking thebottom of the plow furrow, and the pivotal connections of said lowerlink lie in a line generally parallel to a line connecting the pivotalconnections of said upper link while plowing with said upper link beingapproximately one-half the length of said lower link so that the initialmovement of the plow upon striking an ob ject will be upward andrearward followed by a final pivotal movement of said plow presentingthe point of the plow downwardly to aid the plow in clearing itself ofthe object struck.

1. A self-restoring plow trip comprising a supporting frame, a moldboardplow attached to a stub beam, a pair of vertically spaced solid linkspivotally connected at their forward ends to said supporting frame andat their rear ends to said stub beam, biasing means connected betweenone of said links and said frame for biasing said stub beam into plowingposition, in all positions of said plow said pivotal connection of thelower of said links and said frame being positioned forwardly of thepivotal connection of the upper of said links with said frame and saidpivotal connection of said lower link and said stub beam beingpositioned rearwardly of the pivotal connection of said upper link withsaid stub beam whereby when said plow strikes an object said plow willmove rearwardly and upwardly without the point of said plow striking thebottom of said plow furrow, one of said links is provided with a stopmember coacting with said stub beam for limiting the forward movement ofsaid plow under the influence of said biasing means.
 2. A self-restoringplow trip as recited in claim 1 and wherein said upper link is providedwith a hook portion coactable with a member inserted through an openingin said stub beam for retaining said plow in tripped position.
 3. Aself-restoring plow trip comprising a supporting frame, a moldboard plowattached to a stub beam, a pair of vertically spaced solid lInkspivotally connected at their forward ends to said supporting frame andat their rear ends to said stub beam, biasing means connected betweenone of said links and said frame for biasing said stub beam into plowingposition, in all positions of said plow said pivotal connection of thelower of said links and said frame being positioned forwardly of thepivotal connection of the upper of said links with said frame and saidpivotal connection of said lower link and said stub beam beingpositioned rearwardly of the pivotal connection of said upper link withsaid stub beam whereby when said plow strikes an object said plow willmove rearwardly and upwardly without the point of said plow striking thebottom of the plow furrow, said upper link is approximately one-half thelength of said lower link and is vertically spaced therefrom to providesaid plow with a twofold tripping action when an object is struck, afirst action of moving backwards principally while maintaining a plowingaspect of the plow, a second action of pivoting the plow as it is movedrearwardly, and said biasing means comprises a hydraulic cylinderpivotally connected at one end to said frame and pivotally connected atthe other end thereof to a crank arm of one of said links, saidhydraulic cylinder being hydraulically connected to an accumulatorcarried by said frame for providing a hydraulic force resisting upwardmovement of said plow and for storing energy provided by the upwardmovement of said plow.
 4. A self-restoring plow trip comprising asupporting frame, a moldboard plow attached to a stub beam, a pair ofvertically spaced solid links connected at their forward ends to saidsupporting frame rearwardly of the forward point of said plow when inplowing position and said links being connected at their rear ends tosaid stub beam, biasing means connected between one of said links andsaid frame for biasing said stub beam into plowing position andpermitting relief upon striking an object, in all positions of said plowsaid pivotal connection of the lower of said links and said frame beingpositioned forwardly of the pivotal connection of the upper of saidlinks with said frame and said pivotal connection of said lower link andsaid stub beam being positioned rearwardly of the pivotal connection ofsaid upper link with said stub beam whereby when said plow strikes anobject said plow will move rearwardly and upwardly without the point ofsaid plow striking the bottom of the plow furrow, and the pivotalconnections of said lower link lie in a line generally parallel to aline connecting the pivotal connections of said upper link while plowingwith said upper link being approximately one-half the length of saidlower link so that the initial movement of the plow upon striking anobject will be upward and rearward followed by a final pivotal movementof said plow presenting the point of the plow downwardly to aid the plowin clearing itself of the object struck.